A conventional facility network uses a transmission medium of a shared-bus architecture (hereinafter, referred to as a bus) which is generally a narrow band media; and, in order to extend the network, a bridge device is used to connect two physically distinct buses. Such a bridge device has a filtering function not to casually waste bus bands. For example, a bridge device (relay device) described in Patent Document 1 has two transmission/reception means and a storage means that stores the information on terminal devices connected to each of the two transmission/reception means. When a packet is transmitted to a terminal device, the bridge device works so as for the packet to be transmitted only via the transmission/reception means to which the terminal device is connected on the basis of the terminal information stored in the storage means.